Last updated
Age (Ma)
Paleogene Paleocene Danian younger
Cretaceous Upper/
Maastrichtian 66.072.1
Campanian 72.183.6
Santonian 83.686.3
Coniacian 86.389.8
Turonian 89.893.9
Cenomanian 93.9100.5
Albian 100.5~113.0
Aptian ~113.0~125.0
Barremian ~125.0~129.4
Hauterivian ~129.4~132.9
Valanginian ~132.9~139.8
Berriasian ~139.8~145.0
Jurassic Upper/
Tithonian older
Subdivision of the Cretaceous system
according to the ICS, as of 2017. [1]

The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous. [2]

A geologic age is a subdivision of geologic time that divides an epoch into smaller parts. A succession of rock strata laid down in a single age on the geologic timescale is a stage.

In chronostratigraphy, a stage is a succession of rock strata laid down in a single age on the geologic timescale, which usually represents millions of years of deposition. A given stage of rock and the corresponding age of time will by convention have the same name, and the same boundaries.

Stratigraphic column

A stratigraphic column is a representation used in geology and its subfield of stratigraphy to describe the vertical location of rock units in a particular area. A typical stratigraphic column shows a sequence of sedimentary rocks, with the oldest rocks on the bottom and the youngest on top.


The Aptian partly overlaps the upper part of the regionally used (in Western Europe) stage Urgonian.

Western Europe region comprising the westerly countries of Europe

Western Europe is the region comprising the western part of Europe. Though the term Western Europe is commonly used, there is no commonly agreed-upon definition of the countries that it encompasses.

The Selli Event, also known as OAE1a, was one of two oceanic Anoxic events in the Cretaceous period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years. [3] [4] The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma. [5]

Anoxic event Intervals in the Earths past where parts of oceans were depleted of oxygen at depth over a large geographic area

Oceanic anoxic events or anoxic events (anoxia conditions) were intervals in the Earth's past where portions of oceans become depleted in oxygen (O2) at depths over a large geographic area. During some of these events, euxinia, waters that contained H
hydrogen sulfide, developed. Although anoxic events have not happened for millions of years, the geological record shows that they happened many times in the past. Anoxic events coincided with several mass extinctions and may have contributed to them. These mass extinctions include some that geobiologists use as time markers in biostratigraphic dating. Many geologists believe oceanic anoxic events are strongly linked to slowing of ocean circulation, climatic warming, and elevated levels of greenhouse gases. Researchers have proposed enhanced volcanism (the release of CO2) as the "central external trigger for euxinia".

The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous Period is usually abbreviated K, for its German translation Kreide.

The Aptian extinction was an extinction event of the early Cretaceous Period. It is dated to c. 116 or 117 million years ago, in the middle of the Aptian stage of the geological time scale, and has sometimes been termed the mid-Aptian extinction event as a result.

Stratigraphic definitions

The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its crystallized fruits. The original type locality is in the vicinity of Apt. The Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840.

Apt, Vaucluse Subprefecture and commune in Provence-Alpes-Côte dAzur, France

Apt is a commune in the Vaucluse department in the Provence-Alpes-Côte d'Azur region in southeastern France.

Provence Historical province in Provence-Alpes-Côte dAzur, France

Provence is a geographical region and historical province of southeastern France, which extends from the left bank of the lower Rhône River to the west to the Italian border to the east, and is bordered by the Mediterranean Sea to the south. It largely corresponds with the modern administrative région of Provence-Alpes-Côte d'Azur, and includes the départements of Var, Bouches-du-Rhône, Alpes-de-Haute-Provence and parts of Alpes-Maritimes and Vaucluse. The largest city of the region is Marseille.

France Republic with mainland in Europe and numerous oversea territories

France, officially the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean. It is bordered by Belgium, Luxembourg and Germany to the northeast, Switzerland and Italy to the east, and Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic, Pacific and Indian oceans. The country's 18 integral regions span a combined area of 643,801 square kilometres (248,573 sq mi) and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Marseille, Toulouse, Bordeaux, Lille and Nice.

The base of the Aptian stage is laid at magnetic anomaly M0r. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed. The top of the Aptian (the base of the Albian) is at the first appearance of coccolithophore species Praediscosphaera columnata in the stratigraphic record.

Coccolithophore order of algae

A coccolithophore is a unicellular, eukaryotic phytoplankton (alga). They belong either to the kingdom Protista, according to Robert Whittaker's Five kingdom classification, or clade Hacrobia, according to the newer biological classification system. Within the Hacrobia, the coccolithophorids are in the phylum or division Haptophyta, class Prymnesiophyceae. Coccolithophorids are distinguished by special calcium carbonate plates of uncertain function called coccoliths, which are also important microfossils. However, there are Prymnesiophyceae species lacking coccoliths, so not every member of Prymnesiophyceae is coccolithophorid. Coccolithophores are almost exclusively marine and are found in large numbers throughout the sunlight zone of the ocean.


In the Tethys domain, the Aptian contains eight ammonite biozones:

Tethys Ocean Mesozoic ocean between Gondwana and Laurasia

The Tethys Ocean, also called the Tethys Sea or the Neotethys, was an ocean during much of the Mesozoic Era located between the ancient continents of Gondwana and Laurasia, before the opening of the Indian and Atlantic oceans during the Cretaceous Period.


Biostratigraphic unit or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa.

Sometimes the Aptian is subdivided in three substages or subages: Bedoulian (early or lower), Gargasian (middle) and Clansayesian (late or upper).

Lithostratigraphic units

Examples of rock units formed during the Aptian are: Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group and Yixian Formation.



Australiceras Australiceras sp., Late Jurassic to Early Cretaceous, Volga River, Russia - Houston Museum of Natural Science - DSC01900.JPG
Tropaeum imperator Tropaeum imperator.JPG
Tropaeum imperator







Ankylosauria of the Aptian
Cedar Mountain Formation, Utah, USA
Gobisaurus GobisaurusNV.jpg
Minmi Minmi paravertebra dinosauria.png
Sauropelta Sauropelta jconway.png
Ulansuhai Formation, Inner Mongolia, China
Yixian Formation, Liaoning, ChinaNodosaurid with ventral armor plating
  • Minmi
    • Minmi paravertebra
Bungil Formation, Queensland, AustraliaSmall (1 metre (3 feet)) primitive ankylosaur
Aptian to Albian Cloverly Formation, Wyoming, Montana, Utah, USAA medium-sized nodosaurid, measuring about 5 metres (16 feet) long, Sauropelta had a distinctively long tail which made up about half of its body length. Its neck and back were protected by an extensive bony body armor including characteristically large spines

Birds (avian theropods)


Ceratopsia of the Aptian
Mazong Shan, Gansu, ChinaA basal neoceratopsian, appears to have been bipedal and quite small (about 1 metre (3 feet) long) with a comparatively large head. Unlike many later ceratopsians it doesn't have any horns and has only a small bony frill projecting from the back of its head.
Archaeoceratops Archaeoceratops BW.jpg
Auroraceratops Auroraceratops BW.jpg
Psittacosaurus meileyingensis Psittacosaurus meileyingensis BW.jpg
Psittacosaurus meileyingensis
Psittacosaurus mongoliensis Psittacosaurus mongoliensis whole BW.jpg
Psittacosaurus mongoliensis
Xinminbao Group, Gansu, China, South KoreaBasal neoceratopsian
  • Psittacosaurus
    • Psittacosaurus meileyingensis
    • Psittacosaurus mongoliensis
China, Mongolia, RussiaPsittacosaurid Ceratopsian
Victoria, Australia2-metre (7-foot) long early ceratopsian


Choristoderans of the Aptian


  1. Hyphalosaurus lingyuanensis
  2. Hyphalosaurus baitaigouensis
Yixian Formation, Liaoning Province, China
Hyphalosaurus Hyphalosaurus mmartyniuk wiki.png
Monjurosuchus Monjurosuchus.jpg


  1. Monjurosuchus splendens
China and Japan




Mammals of the Hauterivian
several species from Hauterivian to Albian Spain, Mongolia
Jeholodens Jeholodens BW.jpg
Repenomamus Repenomamus BW.jpg
Yanoconodon Yanoconodon BW.jpg
Yixian Formation, Liaoning, ChinaA long-tailed, nocturnal tetrapod (with prensile fingers and toes) which hunted insects, its food, during the night
Yixian Formation, Liaoning, ChinaThe largest mammal known from the Cretaceous period of the Mesozoic, and the one for which there is the best evidence that it fed on dinosaurs.
Yixian Formation, Liaoning, China
Flat Rocks, Victoria, AustraliaThe earliest known monotreme.
Yixian Formation, Hebei, ChinaA small mammal, barely 13 centimetres (5 inches) long. It was lightly built and fed on insects, worms and other invertebrates, probably hunting at night. Like most early mammals, Yanoconodon had short, sprawling legs and claws that were most likely used for burrowing underground or digging


Yixian Formation, Liaoning, China


Ornithopoda of the Aptian


Khukhtek Formation, Mongolia
Atlascopcosaurus Atlascopcosaurus loadsi.JPG
Dollodon Dollodon bampingi Steveoc86.jpg
Iguanodon Sketch iguanodon.jpg
Lurdusaurus Lurdusaurus forelimb.jpg
Mantellisaurus Mantellisaurus atherfieldensis Steveoc.jpg
Ouranosaurus Ouranosaurus head.jpg
Qantassaurus Qantassaurus sketch1.jpg
Tenontosaurus tilletti Tenontosaurus BW.jpg
Tenontosaurus tilletti
Theiophytalia TheiophytaliaType.jpg
Aptian/Albian Eumeralla Formation, Victoria, Australia 2-to-3-metre (7-to-10-foot) long hypsilophodont
Quantou Formation, Jilin, ChinaAs a small basal ornithopod, Changchunsaurus would have been a swift bipedal herbivore, feeding close to the ground.
Barremian-?Aptian Bernissart, Belgium; ?England; ?GermanyA lightly constructed iguanodont, about 6 metres (20 feet) long, estimated to weigh about 1 tonne (1 long ton; 1 short ton)
Mazong Shan, Gansu, ChinaPrimitive hadrosaur or iguanodont
EuropeWorldwide distributed, type genus of the Iguanodontia. 10 metres (33 feet) long
Niger9-metre (30-foot) long heavily built Iguanodont
Atherfield, England, UKformerly known as Iguanodon atherfieldensis
Lakota Formation, South Dakota, USAA genus intermediate between Camptosaurus and more derived iguanodonts.
Echkar Formation, Niger7-metre (23-foot) long hadrosauroid, possibly with a sail on the back
Cedar Mountain Formation, UtahA genus of advanced iguanodont
Victoria, Australia1.8-metre (6-foot) long hypsilophodontid
Xinminbao Group, Gansu, ChinaA hypsilophodontid or other basal ornithopod, Siluosaurus would have been a bipedal herbivore.
  • Tenontosaurus
    • Tenontosaurus tilletti
    • Tenontosaurus dossi
Cloverly Formation, Wyoming and Montana, Antlers Formation, Oklahoma, Twin Mountains Formation, Texas, USA8-metre (26-foot) long early iguanodont
Aptian to Albian Purgatoire Formation, Colorado, USAAn iguanodont described as intermediate in derivation between Camptosaurus and Iguanodon
Cloverly Formation, Montana, USAHypsilophodont


Plesiosaurs of the Aptian
*† Callawayasaurus
    • Callawayasaurus colombiensis
Paja Formation, Colombia8-metre (26-foot) long elasmosaurid
Kronosaurus Kronosaurus bojacens1DB.jpg
Umoonasaurus Umoonasaurus BW.jpg
Aptian to Albian Boyaca, ColombiaAmong the largest pliosaurs, body-length estimates put the total length of Kronosaurus at 9 to 10 metres (30 to 33 feet)
AustraliaRelatively small cryptocleidid, around 2.5 metres (8 feet) long, identified by the three crest-ridges on its skull.



Sauropods of the Aptian
Itapecuru Formation, Maranhão, BrazilA genus of 12 metres (39 feet) long diplodocoid.
Malawisaurus Malawisaurus-head.jpg
Nigersaurus Nigersaurus BW.jpg
Sauroposeidon Sauroposeidon proteles.jpg
Cedar Mountain Formation, Utah; Paluxy Formation, TexasA brachiosaurid
Napai Formation, Guangxi, ChinaProbably a basal titanosaur, known by fragmentary postcranial remains
MalawiTitanosaurid which fossils consist solely of parts of a lower mandible and a few teeth
ArgentinaA basal titanosaurid
MalawiOne of the few titanosaurs for which skull material has been found
Elrhaz Formation, NigerDiplodocoid dinosaur, one of the most common genera found in the rich fossil vertebrate fauna of the Elrhaz Formation
Twin Mountains Formation, Texas, USAA basal titanosauriform
Sao Khua Formation, Thailand
Antlers Formation, Oklahoma, USAThe last known giant brachiosaurid; extrapolations indicate that the head of Sauroposeidon could reach 17 metres (56 feet) in height, making it the tallest known dinosaur. With an estimated length of 30 metres (98 feet) and a mass of 36 to 40 tonnes (35 to 39 long tons; 40 to 44 short tons) it also ranks among the longest and heaviest.
Grès Supérior Formation, LaosA basal titanosaur, known from the remains of two or three individuals.
Cedar Mountain Formation, Utah, USAA titanosaur, known from an incomplete skeleton of an adult and a juvenile


Stegosauria of the Aptian
  • Wuerhosaurus
    • Wuerhosaurus homheni
    • Wuerhosaurus ordosensis
Xinjiang, Inner Mongolia, China7-metre (23-foot) long stegosaurid
Wuerhosaurus Wuerhosaurus.jpg

Non-Avian Theropods

Non Avian Theropods of the Aptian
Texas, Oklahoma, ?Maryland, USALikely an apex predator, up to 12 metres (39 feet) long. Classification disputed (Carcharodontosaurid or Allosaurid)
Acrocanthosaurus Museum of Natural Science Acrocanthosaurus.jpg
Deinonychus Deinonychus BW-2.png
Genyodectes Genyodectes saurus jaws.jpg
Huaxiagnathus Huaxiagnathus-v2.jpg
Kryptops Kryptops BW.jpg
Neovenator Neovenator NT.jpg
Protarchaeopteryx Protarchaeopteryx 4713.JPG
Sinornithoides Sinornithoides-youngi jconway.png
Sinosauropteryx Sinosauropteryx NT.jpg
Suchomimus Suchomimus BW.jpg
Tyrannotitan Tyrannotitan remains 01.png
Utahraptor Utahraptor BW.jpg
Yixian Formation
Cloverly Formation, Montana and Wyoming, Antlers Formation, Oklahoma, Potomac Formation, Maryland, USA3-to-4-metre (10-to-13-foot) long carnivorous dromaeosaurid
Chubut Province, ArgentinaPossibly ceratosaurian
Yixian Formation, Liaoning, ChinaLarge (1.8 metres (6 feet) long) compsognathid
Marree Formation, South Australia, AustraliaA little-known maniraptoran known primarily from a single fossilized tibia, which had been fossilized through a rare process in which the bone through hydration turned to opal. Apart from the tibia, the first find included some small probable fibula fragments. Later a foot digit was referred that might have come from the same species, but the assignment is dubious. The tibia is broken into about ten larger pieces and roughly 33 centimetres (13 inches) long. It is very slender in build and shows the impression of the ascending process of the astragalus, an ankle bone itself lost. The process seems to have been very long and narrow. Kakuru is believed to have been carnivorous, was bipedal and about 2 to 3 metres (7 to 10 feet) in length. This small dinosaur seems to have had long, slender legs.
Elrhaz Formation, NigerEarliest-known abelisaurid
Jiufotang Formation, Liaoning, ChinaSmall (90 centimetres (35 inches) long) feathered dromaeosaurid, possibly the same species as Microraptor zhaoianus

"Nanshiungosaurus" bohlini

Isle of Wight, England, UK7.5-metre (25-foot) long allosaurid
Yixian Formation, Liaoning, ChinaPrimitive oviraptosaur, possibly synonymous with Incisivosaurus
Jiufotang Formation, Liaoning, ChinaCaudipterid oviraptosaur
China1-metre (3-foot) long troodontid
Liaoning, China1.2-metre (4-foot) long compsognathid, fossilized with traces of color pigmentation in its feathers
Tenere, Niger12-metre (39-foot) long spinosaurid
Chubut Province, Argentina12-metre (39-foot) long carcharodontosaurid
North AmericaThe largest known dromaeosaurid
AptianYixian Formation, ChinaA 9-metre (30-foot) tyrannosauroid and the largest dinosaur with feathers preserved

See also

Related Research Articles

The Barremian is an age in the geologic timescale between 129.4 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch. It is preceded by the Hauterivian and followed by the Aptian stage.

In the geological timescale, the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma. It is preceded by the Kimmeridgian and followed by the Berriasian stage.

The Toarcian is, in the ICS' geologic timescale, an age and stage in the Early or Lower Jurassic. It spans the time between 182.7 Ma and 174.1 Ma. It follows the Pliensbachian and is followed by the Aalenian.

The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0.9 Ma. The Albian is preceded by the Aptian and followed by the Cenomanian.

The Gelasian is an age in the international geologic timescale or a stage in chronostratigraphy, being the earliest or lowest subdivision of the Quaternary period/system and Pleistocene epoch/series. It spans the time between 2.588 ± 0.005 Ma and 1.806 ± 0.005 Ma. It follows the Piacenzian stage and is followed by the Calabrian stage.

The Aquitanian is, in the ICS' geologic timescale, the oldest age or lowest stage in the Miocene. It spans the time between 23.03 ± 0.05 Ma and 20.43 ± 0.05 Ma during the Early Miocene. It is a dry, cooling period. The Aquitanian succeeds the Chattian and precedes the Burdigalian.

In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma. The Valanginian stage succeeds the Berriasian stage of the Lower Cretaceous and precedes the Hauterivian stage of the Lower Cretaceous.

In the geologic timescale, the Callovian is an age and stage in the Middle Jurassic, lasting between 166.1 ± 4.0 Ma and 163.5 ± 4.0 Ma. It is the last stage of the Middle Jurassic, following the Bathonian and preceding the Oxfordian.

The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous series. Campanian spans the time from 83.6 to 72.1 million years ago. It is preceded by the Santonian and it is followed by the Maastrichtian.

The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding age. Both age and stage bear the same name.

The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous epoch, or a stage in the Upper Cretaceous series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma. The Turonian is preceded by the Cenomanian stage and underlies the Coniacian stage.

The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma. The Coniacian is preceded by the Turonian and followed by the Santonian.

The Hettangian is the earliest age and lowest stage of the Jurassic period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma. The Hettangian follows the Rhaetian and is followed by the Sinemurian.

<i>Ornithocheirus</i> genus of reptiles (fossil)

Ornithocheirus is a pterosaur genus known from fragmentary fossil remains uncovered from sediments in the UK.

<i>Tropeognathus</i> extinct genus of reptiles

Tropeognathus is a genus of large pterosaurs from the late Early Cretaceous of South America. It was a member of the Ornithocheiridae, a group of pterosaurs known for their keel-tipped snouts, and was closely related to species of the genus Anhanguera. The type and only species is Tropeognathus mesembrinus; a second species, Tropeognathus robustus, is now considered to belong to Anhanguera. Fossils of Tropeognathus have been recovered from the fossiliferous Romualdo Formation of the Araripe Basin in northeastern Brazil.

Tapejaridae family of reptiles (fossil)

Tapejaridae are a family of pterodactyloid pterosaurs from the Cretaceous period. Members are currently known from Brazil, Hungary, Morocco, Spain and China, where the most primitive genera are found, indicating that the family has an Asian origin.

The Cenomanian-Turonian boundary event, or the Cenomanian-Turonian extinction event, the Cenomanian-Turonian anoxic event, and referred also as the Bonarelli Event, was one of two anoxic extinction events in the Cretaceous period. The OAE 2 occurred approximately 91.5 ± 8.6 Ma, though other estimates are given as 93-94 Ma. The Cenomanian-Turonian boundary has recently been refined to 93.9 ± 0.15 Ma There was a large carbon disturbance during this time period. However, apart from the carbon cycle disturbance, there were also large disturbances in the oxygen and sulfur cycles of the ocean.

The Norian is a division of the Triassic geological period. It has the rank of an age (geochronology) or stage (chronostratigraphy). The Norian lasted from ~227 to 208.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.

Timeline showing the development of the extinct reptilian order Pterosauria from its appearance in the late Triassic period to its demise at the end of the Cretaceous, together with an alphabetical listing of pterosaur species and their geological ages.



  1. http://www.stratigraphy.org/index.php/ics-chart-timescale
  2. Gradstein et al. (2004)
  3. Li, Yong-Xiang; Bralower, Timothy J.; Montañez, Isabel P.; Osleger, David A.; Arthur, Michael A.; Bice, David M.; Herbert, Timothy D.; Erba, Elisabetta; Premoli Silva, Isabella (2008-07-15). "Toward an orbital chronology for the early Aptian Oceanic Anoxic Event (OAE1a, ~ 120 Ma)". Earth and Planetary Science Letters. 271 (1–4): 88–100. Bibcode:2008E&PSL.271...88L. doi:10.1016/j.epsl.2008.03.055.
  4. Leckie, R.; Bralower, T.; Cashman, R. (2002). "Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the mid-Cretaceous" (PDF). Paleoceanography. 17 (3): 1–29. Bibcode:2002PalOc..17.1041L. doi:10.1029/2001pa000623.
  5. Archangelsky, Sergio. "The Ticó Flora (Patagonia) and the Aptian Extinction Event." Acta Paleobotanica 41(2), 2001, pp. 115-22.
  6. Mortimer, Mickey. "List of Dromaeosaurids". Archived from the original on October 3, 2011. Retrieved July 8, 2011.